The present invention relates to tone signal synthesis devices suitable for application to various musical instruments such as electronic musical instruments, tone Generation systems, tone processing systems and effectors, and more particularly to such a tone signal synthesis device which synthesizes tone signals on the basis of combination of analyzation and synthesization by the use of a feedback loop system including delay and filter elements.
As methods for generating desired tone waveforms, there is conventionally known one which employs a waveform memory prestoring amplitude values of one or more cycles of tone waveform. This method reproductively produces a tone waveform by repetitively reading out the prestored contents of the memory at a rate proportional to the frequency of a tone to be generated.
A so-called physical model tone source device is also proposed today which synthesizes tone signals by using loop circuitry to electronically approximate physical characteristics of a vibrating object. In this tone source device, delay circuitry is inserted in the loop circuitry to control delay times so that the fundamental pitch of a tone signal is controlled, and filtering elements are also inserted in the loop circuitry to control the tone color.
However, the tone waveform produced by the above-mentioned waveform-readout method is always a mere repetition of a same waveform, and thus, with this method, it is very difficult to generate expressive tones full of variety. Besides, various additional waveform processing must be performed on the tone waveform read out from the memory in order to change the tone color. This waveform-readout method, even if it is combined with the physical model tone source, encounters great difficulty in achieving substantial tonal variety by changing filter constants etc.